Pressure flight control for miniature airplane



Aug. 9, 1955 N. E. .WALKER 2,714,733

PRESSURE FLIGHT CONTROL FOR MINIATURE AIRPLANE Filed July 23, 1951 2 Sheets-Sheet 1 IN VEN TOR.

\ Neville E. Walker BY zm Aug. 9, 1955 N. E. WALKER fi fi PRESSURE FLIGHT CONTROL FOR MINIATURE AIRPLANE Filed July 25, 1951 2 Sheets-Shee 2 INVENTUR. Neville E. We lker United States Patent PRESSURE FLIGHT CONTROL FOR MINIATURE AIRPLANE Neville E. Wailter, Portland, Greg, assignor to American Junior Aircraft Company, Portland, Greg, :1 corporation of Oregon Application July 23, 1951, Serial No. 238,116

4- Claims. (Cl. 46-77) This invention relates to a pressure actuation mechanism, preferably pneumatic, for controlling the flight of a toy airplane from a distance.

It has long been a major objective of the toy or miniature airplane industry to produce an eificient, yet low cost. distant control for directing the flight pattern of a captive or free flight, self-propelled, miniature airplane. In the captive control field, various string or wire type inventions have proven both practical and commercially successful. These include, by way of example, the manual pull, pivot, and reel controls of my prior Patents 2,292,416 and 2,406,874 and the electric relay control of my copending application, Serial No. 781,930, filed October 24, 1947, and since abandoned. In the free flight classiflcation, prior controls have tended toward a more complex and expensive structure such as radio signal control disclosed in my prior Patent No. 2,409,168. Recently, my inventive research has disclosed and has developed yet a third miniature airplane control classification. The controls of this new classification, I have further discovered, possess certain functional and structural advantages impossible to obtain with either a pure captive or a pure free flight type control. Thus, one of the prime objects of my invention is to provide a third type of miniature airplane control, to be called a semicaptive type, which control will improve upon those hitherto known to the industry.

To this end, the semicaptive control differs from the free flight and, in particular, the radio type control both in simplicity of construction and operation and in cost of fabrication. A radio control, for example, must utilize an electric current supply, a radio circuit, together with tubes, condensers, resistors, etc., and a dual antenna system. These elements are expensive and present complex repair problems. Furthermore, the consumers of the toy airplane industry are, in the main, school age children. These children, as a class, possess neither sufficient buying power to develop a high volume market for a radio control nor suflicient mechanical know-how to build and repair the complex radio circuits. Accordingly, one object of my invention is directed toward the provision of an efficient miniature airplane control which is simple, both in operation and repair, and which is inexpensive to fabricate, thus to better serve the needs of school age children.

In differentiation over the prior known captive controls, the instant invention allows an entirely new type of flight, not restricted to a circular pattern or the limits of a taut wire, and allows an improved, more distant control when flight is so restricted to a circular pattern. Thus, the conventional captive airplane, whether electrically or manually controlled, flies at the end of one or more flight limiting strings or wires. To vary the flight pattern, more or less pull or tension is applied to the wire or wires. The prime disadvantages of this operation are dual and both flow from the fact that a tension always must be maintained in the control lines since no force can be transmitted over a slack line. To illustrate this disadvantage, the conventional Wire control includes a hand grip having two or more elongated wires leading from spaced portions thereof, through a guide on the Wing or fuselage, to the elevators and/or to the ailerons of the miniature airplane. To cause the airplane to climb, descend, or describe other maneuvers, the operator pulls upon or increases the tension in the appropriate wire to actuate the corresponding control. If the control wires become slack, the response is sluggish, and an excessive slack may even cause the airplane to be dragged down or to nose over and crash.

The first of the dual disadvantages above described stems from the fact that the control wire or wires must be taut. Conventionally, this limits the flight pattern of the miniature airplane to a circle or ellipse with the operator in the center. Secondly, the dead weight and air resistance of the control wire per selimit the radius of the flight circle or the distance from which a quick response may be dictated. In practice, wire lines, such as piano wire, become inefficient and the control becomes sloppy if more than sixty feet are payed out. Furthermore, a miniature toy airplane is pulled toward the operator or toward the center of the flight circle if the control line weighs too much. The instant invention, on the other hand, does not depend upon a constant tension control line. Furthermore, the control line itself, a hollow tube, is even lighter in weight than fine wire so very little pull or drag is impressed upon the small toy. Accordingly, the flight path is not limited to a circle and much more distant actuation, in excess of feet is practical and efficient. It is because this novel control need not limit the flight path by the maintenance of a constant tension that I have termed it a semicaptive control.

In attaining the above inventive objects, the instant control preferably is pneumatic in function and it includes one or more expansible hollow bags secured to the control surfaces of a miniature airplane. An elongated, hollow pressure tube is connected at one end to each such bag for flight with the airplane. The opposite end of the hollow tube, on the other hand, leads from the airplane to a distant actuation or control station, say 100 feet away. At this station, a hollow air bulb, tire pump, piston and cylinder or other pressure supply and exhaust means is joined to the tube alternately to supply pressure to or subtract pressure from the hollow tube. Thus, by controlling the an or fluid pressure in the tube, the expansion or contraction of the corresponding hollow bag is effected to move the control surface secured thereto. By way of example, one hollow bag may be secured to the elevators of the airplane and these elevators may be spring biased to one predetermined operative position. Thereafter, the supply or exhaust of pressure fluid to the bag will overcome the spring bias to cause the airplane to dive, climb or fly level when the elevators are manipulated as desired. The advantages of such a pneumatic, semicaptive control at once are apparent. It is simple yet efficient in operation, of minimum construction cost, and is not dependent upon a tension in the hollow tube to secure a tight, quick response.

Other advantages of my invention will appear as the following detailed description unfolds. Such description will be taken with respect to the preferred embodiments disclosed in the accompanying drawings, wherein:

Fig. l is a perspective view of a miniature toy airplane equipped with the pressure control of my invention as applied to the elevator of such an airplane;

Fig. 2 indicates the other end of the elongated, hollow pressure tube which leads from the miniature airplane to a distant actuation means such as the resilient and compressible hollow bulb shown connected thereto in said figure;

Figs. 3, 4, and 5 are detail views, partially broken away, indicating the three operative positions of the elevator of a miniature airplane as controlled by a first species of my invention; said three positions being a raised or climb position, an intermediate or level flight position, and a lowered or dive position; and

Figs. 6,. 7, and 8 are detail views, also partially broken away, illustrating the three operative positions of the elevator of a miniature airplane as controlled by a second species of my invention.

In the drawings accompanying this specification, I have shown the two species of my invention applied to the control of the elevator of a miniature airplane. To this end, the airplane 1 includes an elongated fuselage 2, a main wing 3, a rudder 4, and a horizontal stabilizer 5 having an adjustable elevator 6. To those skilled in the art, however, it will be apparent that this invention is equally practical to control the ailerons and/ or the rudder of such an airplane. I have illustrated an elevator control, however, since the majority of those miniature airplanes now on the market are equipped with adjustable elevators whereas many of them do not have adjustable ailerons or rudders.

In accord with conventional practice, the major portions of the airplane 1 are constructed from balsa wood, thin sheet metal, or light plastic and the fuselage 2 is pierced by an elongated slit 7 frictionally to accommodate the main wing 3. Further to inhibit lateral movement of the wing 3 within the slit 7, a piece of adhesive or gurnrned tape 8 is fixed on each side of the fuselage 2 to the fuselage and wing.

Progressing rearwardly along the fuselage 2', a metal clip 9 is fixed to the tail. This metal clip terminates in a cupped pocket 10 disposed immediately below the elevator 6. Additionally, the forward portion of the clip 9 defines a hollow tunnel 11 through which one end of an elongated hollow pressure tube 13 is threaded.

In both species of my invention the hollow tube 13 is clipped to the underside of the fuselage 2, as by the staples 14, to lead the tube forwardly toward the main wing 3. A guide clip 15' detachably grips one side of the wing 3 and is provided with an aperture or guide hole 16 through which an intermediate portion of the tube 13 is threaded. Thus, the tube is made to lead' away from the airplane approximately opposite the center of mass so an aerodynamic stability will be evidenced should the tube be used as a flight limiting line.

Progressing now to Figs. 2, 3, 4, and 5, the respective ends of the tube 13 are joined to a resilient and compressible hollow bulb or distant actuation means 17 and to an expansible rubber or plastic bag 12. Intermediate the bulb 17 and tube 13, a detachable fitting 18' is pro vided for disconnecting these two elements. Additional ly, it will be noted, the hollow bag 12- fits within and is carried by the cupped pocket 10 in the metal clip 9. Thus, the elevator 6 is hinged, as by means of a length of adhesive or gummed tape 19, to pivot and move with respect tothe horizontal stabilizer 5 and to cause the airplane to dive and climb. Thereafter, a small disk 20 is glued or otherwise secured to the undersurfaceof the elevator 6 and a leaf spring or resilient wire 21 is fixed to the tail and caused to bear upon the elevator 6 to' define a bias. In the first species of my invention, this biasof: spring 21 is suflicient to collapse the bag 12 and depress the elevator 6 when atmospheric pressure exists within the hollow tube 13.

In operation it will be assumed that air is the pressure medium utilized to inflate and deflate the expansible hollow bag 12 although some operators may prefer a gas or other light weight fluid. Thus, when the control is assembled by securing the hollow bulb 17 to the tube 13 with the detachable fitting 18,. atmospheric pressure will be present throughout the length. of the tube 13, within the bag 12, and within the hollow bulb 17 and the elevator 6 will be in the position of- Fig. 5. As is conventional, the airplane 1 is provided with a gasoline,

diesel or other type engine 23. This engine is started when the airplane is to be flown. At the take-inf, the operator squeezes the hollow bulb 17 to inflate and expand the bag 12 and raise the elevator 6 to the position of Fig. 3. This manipulation causes the airplane to climb. After the airplane reaches a suflicient height, the pressure on the hollow bulb 17 is backed off somewhat, by slightly releasing the grip or squeeze thereon, and the elevator 6 will assume the position shown in Fig. 4 for level flight. Acrobatics, such as loops, can be effected by the proper manipulation of the hollow bulb 17 to impress more or less pressure upon the bag 12. Furthermore, the elongated, hollow pressure tube 13 may serve a second function as a flight limiting line should the operator desire to fly the airplane in a circle. If, on the other hand, the operator merely wishes to shoot landings or to run or ride with the bulb 17 in his hand, the presture tube 13 need not serve as a flight limiting line. This is for the reason that accurate control of the elevators is in no way dependent upon the maintenance of a tension in the tube 13. It is for this reason that I have termed this type of control semicaptive.

In the second species of my invention, a second hollow bulb 27 and a second expansible bag 22 are utilized. This second hollow bag 22 (see Figs. 6, 7 and 8) has a small disk or ball of sponge rubber or other elastic 24 carried therein. This sponge disk occupies approximately one-half the volume of the expanded bag 22 as shown in Fig. 6. Thus, the sponge exerts a second bias force upon the disk 20 and the elevator 6 in opposition to the bias force of the leaf spring 21. By carefully correlating these two bias forces, the elevator 6 can be made to assume the intermediate or level flight position of Fig. 8 when atmospheric pressure exists within the tube 13, bulb 27, and bag 22. I deem this intermediate bias to be of substantial importance since a deadman control thereby is provided, and the airplane will fly straight and level should the tube 13 break inadvertently.

In the operation of the second species of my invention, the elevator 6 will assume the intermediate position of Fig. 8 before the hollow bulb 27 is connected to the tube 13. Accordingly, the bulb 27 is depressed or squeezed slightly before the detachable fitting 18 is joined thereto to connect the parts. Thereafter, if the bulb 27 is released (see Fig. 7), a pressure less than atmospheric pressure will exist within the hollow tube 13 since the bulb will draw air from the tube and from the bag 22. However, the raised" position of Fig. 6 still may be defined by squeezing the bulb 27 tightly to exert a pressure greater than atmospheric upon the bag 22. This second species of my invention, then, functions similarly to the first species except that a deadman control is provided so the miniature airplane will not crash should some of the parts of the control. break inadvertently.

In service of my inventive objects, the elongated, hollow pressure tube 13 is best formed from a light plastic material so the weight thereof will not tend to pull the airplane toward the operator. Such a tube, in combination with my other inventive elements, possesses the further advantage of allowing a miniature airplane to be flown at a great distance from the operator. Thus, the quick and accurate response of the expansible bags 12 and 22 is in no way dependent upon the tension of the tube 13. Instead, such' response is dependent upon the relative pressure supplied to' these bags from the hollow bulbs 27 or their equivalent. In flying a miniature airplane with this novel control, it will be noted, the flight pattern need not be limited to a circle. For example, the operator may practice dead stick landing by timing. the engine 23 to cut out after a short flight. Accordingly, by proper manipulation of the bulb 17 or 27, the airplane 1' may be caused to take off, fly level, and land all in a straight line. The only requirement for such a flight is that sufficient hollow tubing 13 be provided. Furthermore, in direct contrast With some of the complex controls of the prior art, my pneumatic or semicaptive control is simple in operation and repair and is inexpensive to fabricate. Both of these advantages serve the needs of the typical school age child consumer thereby to provide an eflicient, low cost distant control such as has long been sought by the miniature toy airplane industry.

I claim:

1. A pneumatic flight control mechanism for a semicaptive miniature airplane having means for producing self-sustained flight, comprising an adjustable elevator mounted upon said airplane and movable between a raised and a lowered position to control the vertical component of the flight pattern of said airplane while the airplane is airborne, elastic means for biasing said elevator toward a position between said raised and lowered positions, and expansible and collapsible pneumatic means responsive to a distant means for increasing and decreasing the air pressure above and below atmospheric selectively to move said elevator to either one of said raised and lowered positions against said bias.

2. In combination, a pneumatic flight control mechanism for a semicaptive and self-propelled, laterally stable, miniature airplane capable of self-sustained flight, an adjustable elevator mounted upon said airplane and movable between a raised and a lowered position to control the vertical component of the flight pattern of said air plane while the latter is airborne, elastic means operative at atmospheric pressure to bias said elevator to a position intermediate said raised and lowered positions, and expansible and contractable air containing means bearing on said elevator and responsive to a distant means for increasing and decreasing the air pressure above and below atmospheric selectively to move said elevator to either one of said positions against said bias.

3. A pneumatic flight control mechanism for a laterally stable miniature airplane having means for producing self-sustained flight comprising an adjustable elevator mounted upon said airplane and movable between a raised and a lowered position to control the flight pattern of said airplane, elastic means for biasing said elevator to a position intermediate said raised and lowered positions, an elongated, hollow air tube having a first end carried by said airplane and a second end located distantly therefrom, an inflatable and deflatable pneumatic means operatively joined to said elevator and connected with said air tube first end selectively to move said elevator between said positions against said bias in response to and in proportion to the air pressure in said tube, and distant actuation means joined to said air tube second end selectively to vary the air pressure in said tube, said actuation means including a resilient and compressible hollow bulb detachably connected with said air tube.

4. A pneumatic elevator control operative during flight to steer a semicaptive miniature airplane having means for producing self-sustained flight, comprising an elevator means movable between a raised, an intermediate, and a lowered position to control the flight of said airplane, dead man means operable at atmospheric pressure to bias said elevator to said intermediate position, and distantly actuated pneumatic means bearing on said elevator and responsive to an air pressure less than or more than atmospheric, respectively, to move said elevator against said bias to one of said other positions from said intermediate position.

References Cited in the file of this patent UNITED STATES PATENTS 1,796,157 Moore Mar. 10, 1931 2,364,233 Morey Dec. 5, 1944 2,476,678 Miller July 19, 1949 FOREIGN PATENTS 376,701 Italy Nov. 23, 1939 529,284 Great Britain Nov. 18, 1940 

